1. Field of the Invention
This invention relates to a safety seat belt system, particularly, to a safety seat belt system suitable for use in vehicle.
2. Description of the Prior Art
Motor vehicles are generally equipped with a safety seat belt system for protecting vehicle occupants at the time of emergency like a collision. The recent trend toward the economy of energy and natural resources is reflected by an increasing demand for motor vehicles of smaller size and weight. As a matter of course, the safety seat belt systems for smaller cars have various restrictions, for example, the limited mounting space. In this regard, various attempts have been made to provide a compact retractor for the webbing of the safety belt system.
One attempt is to vary the width of the webbing stored in the retractor from that of the restraining webbing section which is to be worn around the occupant. More particularly, the occupant-restraining webbing is generally required to be about 50 mm in width for suitably dispersing and absorbing the impact force as applied to the occupant at the time of a sudden deceleration. Its width may gradually be reduced in the intermediate section and finally to, for example, about 25 mm in the stored section which is received in the retractor, thereby permitting to reduce the size and weight of the retractor and thus the mounting space of the retractor commensurately with the reduction in the webbing width in the storing section.
However, in a safety seat belt system using a continuous webbing which integrally consists of a shoulder webbing for restraining the torso of a vehicle occupant and a lap webbing for restraining the front part of the lower trunk and thighs of the occupant, a substantial length of a narrow webbing section has to be extended from the retractor in order to encircle a restraining body portion (normally the torso) of the occupant so that the narrow webbing section may extend over the restraining body portion and there is thus a possibility of the webbing failing to protect the occupant by sufficiently dispersing the impact force which would be imposed on the occupant by a sudden change in the vehicle speed as in the case of a collision. Restraint of the occupant by a broad webbing naturally results in a shorter length of the narrower webbing section and a difficulty of taking up the extended broad webbing section in the retractor in an unrestraining state, leaving on the seat a lengthy webbing untidily which might get in the way of the occupant when getting on and off the vehicle or block the viewfield to cause a trouble at the time of safety confirmation or the like.